Problem: $ { \left[\begin{array}{rr}{1} & {0} \\ {-2} & {-2}\end{array}\right]-\left[\begin{array}{rr}{-2} & {-1} \\ {2} & {2}\end{array}\right] = {?} } $
Answer: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rr}{1}-{-2} & {0}-{-1} \\ {-2}-{2} & {-2}-{2}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{3} & {1} \\ {-4} & {-4}\end{array}\right]}$